Coaxial cable television systems have been in widespread use for many years and extensive networks have been developed. The extensive and complex networks are often difficult for a cable operator to manage and monitor. Particularly, a typical cable network generally contains a headend which provides content to a cable modem termination system (CMTS) containing several receivers, each receiver is usually connected to modems of many subscribers, e.g., a single receiver may be connected to hundreds of modems. In many instances the operator will cable multiple receivers together to serve a particular area of a town or city.
Cable operators often use Load Balancing Groups and/or Spectrum Groups to equalize the load of the traffic across receivers and is a feature that is tested for DOCIS 2.0 by Cable Labs. Load Balancing is often performed by a software program controlled by cable operators to help prevent one or more receivers from being overloaded with data while other receivers are being underused. In order to have receivers belong to the same Load Balancing Group or Spectrum Group all of the receivers in the group must be physically wired together in the RF head end. Multiple receivers in Load Balancing and Spectrum Groups may be used for agility whenever the CMTS detects that an individual receiver has excessive loads, such as excessive data traffic.
In order for cable operators to take advantage of the Load Balancing features they have to first manually configure every Load Balancing Group and/or Spectrum Group. For example, the Motorola BSR 64000 has 12 slots available for CMTS cards with 8 receivers on each card. The worse case scenario, but a common one, would be that the operator has to configure 48 Load Balancing Groups, with two upstreams per Load Balancing Group and/or 48 Spectrum Groups. These are time consuming efforts that can also be prone to errors for the cable operator. In some instances cable operators may not want to take advantage of these features because they do want to expend the resources to perform the manual configuration.
There is presently no suitable technique for determining if a receiver designated to a Load Balancing Group or Spectrum Group is actually capable of carrying the loads required. For example, if a receiver R1 in a Load Balancing Group has an excessive load a CMTS operator may shift portions of the load on R1 to receiver R2 in the Load Balancing Group by attempting to register several modems M associated with R1 to R2. However, if receiver R2 has a poor RF connection, such as a damaged coaxial cable, the modems M will deregister from receiver R2 and re-registered again on receiver R1. Without operator intervention, the load balancing operation is caught in an endless cycle of registering/deregistering modems between R1 (being overloaded) and R2 (connected with a bad cable) resulting in numerous modem deregistration. The CMTS operator must determine which receiver has failed, the cause of the failure, and manually remove the failed receiver from the Load Balancing Group. Even if a CMTS could detect a bad cable directly at the input of the receiver, presently, no CMTS's are known to be able to detect bad or missing cables further down the RF plant.